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-rw-r--r--indra/llcommon/llpreprocessor.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/indra/llcommon/llpreprocessor.h b/indra/llcommon/llpreprocessor.h
index 5eefa6a16b..1c1503ca7b 100644
--- a/indra/llcommon/llpreprocessor.h
+++ b/indra/llcommon/llpreprocessor.h
@@ -55,13 +55,28 @@
#define LL_BIG_ENDIAN 1
#endif
+
// Per-compiler switches
+
#ifdef __GNUC__
#define LL_FORCE_INLINE inline __attribute__((always_inline))
#else
#define LL_FORCE_INLINE __forceinline
#endif
+// Mark-up expressions with branch prediction hints. Do NOT use
+// this with reckless abandon - it's an obfuscating micro-optimization
+// outside of inner loops or other places where you are OVERWHELMINGLY
+// sure which way an expression almost-always evaluates.
+#if __GNUC__ >= 3
+# define LL_LIKELY(EXPR) __builtin_expect (!!(EXPR), true)
+# define LL_UNLIKELY(EXPR) __builtin_expect (!!(EXPR), false)
+#else
+# define LL_LIKELY(EXPR) (EXPR)
+# define LL_UNLIKELY(EXPR) (EXPR)
+#endif
+
+
// Figure out differences between compilers
#if defined(__GNUC__)
#define GCC_VERSION (__GNUC__ * 10000 \